1. Field of the Invention
This invention relates to the chemical analysis of substances, and more particularly, to a method and apparatus for storing analysis slides on an analyzer and for delivering analysis slides to a slide distributor in the analyzer.
2. State of the Prior Art
Recent developments have provided analysis slides for use in performing quantitative analyses of biological fluids. The slides are essentially planar, contain reagents in dry form, and can be loaded into a cartridge for use in a chemical analyzer. In the operation of such an analyzer, an analysis slide is fed from a cartridge into a metering station where a predetermined amount of sample fluid is deposited on the analysis slide. After an appropriate incubation period, the slide is moved to an analysis station where a change in the slide is sensed, the amount of change being proportional to a particular analyte in the sample fluid. The slide is used only once and is discarded after the reading is taken. An analyzer for use with slides of this type is described in commonly-assigned U.S. Pat. No. 4,296,070, granted on Oct. 20, 1981.
In performing analyses, as described above, a different type of slide is needed for each of the analytes. Thus, in an analyzer of the type described, a cartridge of analysis slides must be carried on the analyzer for each of the desired tests, or assays. In high-throughput analyzers performing a large number of different tests, it may be necessary to store as many as fifty cartridges, each cartridge containing slides for a particular test. There is a problem in storing so many cartridges in a limited space and in such a manner that a slide can be removed from a selected cartridge for a desired test. In prior art devices, cartridges have been mounted on a turntable and the turntable is rotated to move a selected cartridge into an unload station. Such a device is shown in U.S. Pat. No. 4,224,032. In the device disclosed in this patent, however, the cartridges can only be mounted in a single ring on the outer periphery of the turntable, since the cartridges must cooperate with a slide feeding mechanism located radially inward of the cartridges. Thus, the number of cartridges which can be mounted on the turntable is limited.
It is an object of the present invention to overcome the above-described problems in prior art devices and to provide a novel method and apparatus for storing a relatively large number of cartridges in an analyzer and for dispensing slides from the cartridges.
In accordance with the present invention there is provided in a chemical analyzer for measuring a characteristic of a sample fluid wherein the fluid is deposited on an analysis slide which is analyzed after an appropriate period of time, the combination comprising: means for supporting a plurality of stacks of slides adjacent each other, each of the stacks having a longitudinal axis; means for removing a slide from a selected stack, the removing means being movable along a path generally transverse to the axes; and means for positioning the selected stack and the removing means relative to each other and to the supporting means such that a slide from the selected stack is in a position to cooperate with the removing means.
In accordance with the present invention, there is also provided a method of dispensing analysis slides from a slide supply in a chemical analyzer, the method comprising the steps of: loading a plurality of stacks of slides onto a support means in the supply; positioning one of the stacks relative to the other stacks and to the support means such that a selected analysis slide in the one stack is accessible to a slide removal means; and removing the selected slide from the stack and delivering the slide to a slide distributor.
In one embodiment of the invention, concentric rings of cartridges are mounted on a rotor which can be driven to move cartridges to an unload station; at the unload station, a lift mechanism is provided to move a selected cartridge into a dispense position such that its uppermost slide is in the path of a dispense blade. The dispense blade is adapted to remove the slide from the cartridge and deliver the slide to a slide distributor.
The disclosed invention is particularly advantageous for use in analyzers in which a large number of cartridges of slides are stored on the analyzer and each of the cartridges must be quickly and easily accessible for the removal of a selected slide. The cartridges are supported in a rotor, and the slide removal means is located relative to the rotor such that substantially the entire rotor can be used for storing cartridges.